In the industrial stripping sector, shutters, windows, doors and radiators are stripped, as is any mechanical component (e.g.: wheel hubs, wheel rims, etc.). The industrial stripping of paints and the like is carried out by immersing the components to be stripped in a liquid bath formulated under hot or cold conditions, it being possible for this liquid bath to be stirred or not to be stirred. The components are left in the bath for a certain period until stripping is achieved (degradation or removal of the paint, depending on the systems). Next, the components are removed from the bath and are rinsed with a jet of pressurized water ("carcher"), the flakes or lumps of paint then being removed by the pressure of the water jet. When the bath contains a strong base of the NaOH type, a neutralization operation is carried out in an acid bath consisting of a solution of sulphur or hydrochloric acid.
The formulation currently used in industrial stripping are either chloride-based or alkali-based. Chloride baths or formulations are mixtures based on methylene chloride, methanol (5 to 10% by weight) and aromatics (toluene, xylene in a proportion of a few percent). The mixtures can also contain activators, which can be acidic (such as formic acid) or basic (such as monoethanolamine). Chloride baths are used cold since methylene chloride is very volatile and the odor it gives off is highly suffocating. The stripping action takes place by removal of the paint with formation of flakes. Industrial stripping technicians currently wish to replace chloride by a substitute for environmental reasons.
Alkaline baths or formulations are essentially based on sodium hydroxide in water to which are added sodium glycolate, complexing agents and wetting agents. The mixtures are used hot, at a temperature of about 50.degree. C. to 100.degree. C., and the stripping time is halved for every 20.degree. C. rise in temperature.
The mechanism of action is totally different to that of the chloride formulations since these formulations degrade the paint by reaction of the sodium hydroxide with the polymer.
In particular, with glycerophthalic paints and alkyd paints, saponification of the ester functions takes place, which degrades the paint, reducing it to powder. When dispersed in the bath, this powder forms a sludge, which is a pet hate of stripping technicians. This sludge is virtually unfilterable (blocking). Moreover, alkaline formulations are less effective on other types of paint (epoxy, polyurethane, etc.). Industrial stripping technicians thus also wish to find a substitute formulation of greater versatility which does not lead to degradation of the paint.